It is a matter of general knowledge to appropriately use lubricant for a rotary shaft, a sliding face of a piston and a frictional face of a gear or a cam in a power tool such as an electric tool or a pneumatic tool. Concerning this matter, for example, refer to JP-A-2003-136435. In the case of lubrication of a rotary shaft or a sliding member, the sliding speed of which is relatively low, to which a heavy load is given, provided in a binding wire twisting mechanism of a reinforcing bar binding machine, grease of higher viscosity is used.
In the case where the reinforcing bar binding machine is used outside where a temperature is very low, the viscosity of grease is increased and a sliding resistance of a rotary shaft or a sliding member is raised. Accordingly, it becomes impossible to exhibit the original performance of the binding machine. In the environment of low temperature, a battery voltage is reduced and an output of a motor is lowered. Accordingly, in addition to the increase in the viscosity of grease, due to the reduction in the battery voltage, an operation speed of a mechanism portion is decreased and further an operating force of the mechanism portion becomes weak. Consequently, there is a possibility that failure in operation is caused and further it becomes impossible to start the binding machine.